METALLURGY OF IRON" AND STEEL.
in Fig. XVII-G together with 'the final results on basic steel. The value of carbon for acid metal is shown by the tangent of the line with the horizontal, and is about 1000 pounds for each .01 per cent. The line intersects the zero ordinate at 40,000 pounds.
TABLE XVII-T. • Effect of Carbon upon Acid Steel.
NOTE,—In calculating the last column a value of 1000 pounds is given to 0.01 per cent, of phosphorus; manganese is rated according to Table XVII-R.
Class. Chemical composition ; per cent. Ultimate strength : pounds per square inch.
Carbon. Phosphorus. Manganese. Actual records. After deducting for phosphorus and manganese.
Acid test-bars; carbon by combustion. 0.1520 0.1713 0.2486 0.3268 0.3609 0.3943 0.4357 0.4693 0.5130 0.0565 0.0570 0.0537 0.0480 0.0443 0.0419 0.0384 0.0371 0.0358 0.440 0.453 0.497 0.529 0.528 0.526 0.519 0.518 0.513 61806 63637 72185 80626 83886 87155 91278 95052 99795 55676 57216 64875 72472 75744 78996 83273 86917 91605
EFFECT OF MANGANESE ON BASIC STEEL.
•The bars were classified according to their content of manganese as shown in Table XVII-TJ and in Fig. XVII-E. The line of very low-carbon and low-manganese steels shows that in the absence of manganese the strength is raised by iron oxide or by some other agent. In steels of higher carbon less oxygen is present, owing to the protecting power of carbon, and the decrease in strength with decrease in manganese holds good down to a content of 0.3 per cent. Considering only the lines representing steels with from 0.075 to 0.224 per cent, and with from 0.325 to 0.374 per cent, of carbon, and pursuing the same course of reasoning as explained in the valuation of manganese in acid steels, it appears that above the limit of 0.3 per cent, of manganese the effect of each unit of that element is greater in the steels of higher carbon. In the acid steel the value at zero carbon was zero, the effect of 0.01 per cent, of manganese in a steel of 0.1 per cent.' of carbon was 80 lb., and this effect increased 8 lb. with each rise of 0.01 per cent, of carbon.
In basic steel the value of 0,01 per cent, of manganese at zero